Method and apparatus for loading a well perforator



May 20, 1969 J. R. HAKALA 3,444,810

METHOD AND APPARATUS FOR LOADING A WELL PERFORATOR Filed Sept. 8, 1967 INVENTOR JOHN R. HAKALA AMQLAJ ATTORNEY 3,444,810 METHOD AND APPARATUS FOR LOADING A WELL PERFORATOR John R. Hakala, Fort Worth, Tex., assignor to Harrison Jet Guns, Inc, Houston, Tex., a corporation of Texas Continuation-impart of application Ser. No. 461,941,

June 7, 1965. This application Sept. 8, 1967, Ser.

Int. Cl. E21b 43/26; F42c 3/00 US. Cl. 10220 Claims ABSTRACT OF THE DISCLOSURE Cross-reference to related application This application is a continuation-in-part of applicants copending application Ser. No. 461,941, filed June 7, 1965, entitled Perforating Means for Sand Control.

Field of the invention This invention relates to well perforators, and more particularly to improvements in the loading of shaped charge units into the gun barrels of well perforators.

The prior art It has heretofore been known to dispose a plurality of shaped charge units in ports along the length of a gun barrel which is adapted to be lowered into a well bore hole to be perforated. Each of the shaped charge units is connected to successive points along the length of an elongated detonating tfuse disposed inside the gun barrel. The construction of these previously developed perforators has generally required that the detonating fuse be threaded through an opening in one end of each of the shaped charge units. Such construction has necessitated time consuming loading of the perforators due to the fact that a plurality of shaped charged units must be strung along the length of the detonating fuse at predetermined points, inserted into the ports from the interior of the gun barrel, and then fastened to the gun barrel by the addition of separate threaded caps. Exemplary systems of this type are described and disclosed in US. Patent No. 2,782,715, issued Feb. 26, 1957; and US. Patent No. 2,844,098, issued July 22, 1958. Other systems have attempted to eliminate these problems in loading by providing units which may be loaded from the exterior of the perforator. However, these units, as exemplified by US. Patent 2,764,937, issued Oct. 2, 1956, have also required separate threaded caps and have often been difficult to properly connect to the detonating fuse. The large number of separate charge units and threaded caps required for such perforators 3,444,819 Patented May 20, 1969 often creates warehousing and handling problems, in addition to increasing the difiiculty in final assembly.

In an effort to simplify the loading of well perforators, gun perforators have heretofore been developed wherein a plurality of shaped charge units may be inserted from the exterior of the gun barrel into ports positioned in substantially the same plane. The ends of each of the shaped charge units extend generally to the center of the gun barrel and the elongated detonator fuse extending through the gun barrel is centered between and contacts the ends of each of the shaped charge units. Such a perforator is described and disclosed in applicants previously identified copending application Ser. No. 461,941, filed June 7, 1965. While such perforators have greatly simplified the loading of shaped charge units, it would be desirable to facilitate peiforator loading without the requirement of a plurality of shaped charge units disposed about a gun barrel in the same plane.

Summary In accordance with the present invention, a perforator gun barrel is provided with explosion ports in the walls thereof and an elongated fuse is extended through the barrel. A cap member is adapted to be received in one of the ports and supports a tubular casing having a diameter less than the diameter of the port. The casing has a truncated cone-shaped end portion disposed opposite the cap member containing a hollow cone-shaped charge of explosive the apex of which is directed away from the cap member. A clamp member is swiveled on the end of the tubular casing and is adapted to secure ly receive a portion of the fuse.

In accordance with the present method of loading the shaped charge units into the gun barrel, a loop of the fuse is drawn to the outside of the barrel through one of the ports. The end of one of the shaped charge units is connected to the loop of fuse and the shaped charge unit is inserted into the port.

The drawings Referring to llIGUR-E 1, the well perforator according to the invention is designated generally by the numeral 10. The well perforator is of the general type disclosed in the previously identified copending application Ser. No. 461,941, wherein a cable adapter head, an intermediate gun barrel section, and a lower enclosure member are secured together to provide an elongated rigid assembly which may be lowered into a well bore. An electrical circuit (not shown) extends from the perforator to the surface for energizing a fuse and detonating successive shaped charge units disposed in the intermediate barrel section.

FIGURE 1 illustrates a sectional view of the intermediate gun barrel section 12 loaded with a shaped charge unit 14. The shaped charge unit 14 is shown in section and includes a cap member 16 having an enlarged circular head 18. The cap member 16 includes a threaded body 20 which is received by a threaded port 22 defined through the wall of the gun barrel 12. It will be understood that a number of ports will be defined through the wall of the gun barrel at spaced intervals along the length thereof, some of the iPOl'tS being offset from the position of port 22 in order to provide the desired pattern of perforations in the casing walls.

A countersunk portion 24 provided in the port 23 receives a washer 26 made from resilient material in order to provide sealing and preventing the entry of sand or bore hole fluids. The depth of the countersunk portion 24 and the thickness of the washer 26 are such that the head 18 may sit generally flush with the surface of the gun barrel 12.

A tubular casing 28 is supported by the cap member 16 to form a unitary shaped charge unit of a diameter which may be inserted into the interior of the gun barrel 12 through the port 22. The tubular casing 28 includes a truncated cone-shaped end 30 having a hollow portion filled with an explosive charge 32. The explosive charge 32 is formed into a hollow cone configuration which receives a cone-shaped metallic liner 34. Upon detonation of the explosive charge 32, the metallic liner 34 forms a particle jet which perforates the central portion of the head 18 of the cap member 16 to form a hole in the adjacent well bore casing.

In accordance with the present invention, an annular groove 36 is formed about the end portion of the coneshaped end 30. A swivel clamp base 38 is rotatably mounted on the end 30 by means of an annular flange 39 which fits into the groove 36. A pair of resilient prongs 40 are connected to the base 38 to form a unitary swivel clamp. The prongs 40 are spaced apart a predetermined distance in order to clamp and provide a small compressive force to the detonation fuse 42.

The prongs 40 are preferably constructed from resilient metal and include curved portions in order to securely fit about peripheral portions of the fuse 42. The outer ends of the prongs 40 are outwardly curved to enable attachment to the fuse 42 without damaging the protective casing of the fuse. The dimensions of the prongs 40 are such that the fuse 42 is closely held to the explosive charge 32 in order to insure proper detonation of the shaped charge unit.

FIGURE 2 illustrates the method of loading the present well perforator with shaped charge units. The elongated detonation fuse 42 is first strung through the interior length of the gun barrel 12. A tool 44 includes a hook portion 46 which is then inserted through the port 22 and hooked about the fuse 42. A loop of the flexible fuse 42 is then drawn through the port 22 to the exterior of the gun barrel 12. The swivel clamp prongs 40' of a shaped charge unit 14 are then manually clamped onto the loop of fuse extending from the port. The tool 44 is removed from the fuse 42, and the shaped charge unit 14 is then inserted through the port 22, thereby disposing the loop of the fuse 42 back inside the gun barrel 12. The shaped charge unit 14 is then tightly screwed into the port 22. Due to the swivel connection between the end 30 and the base 38 of the clamp, the fuse 42 will not rotate or twist as the shaped charge unit is being served into the port 22.

It will be understood that the provision of the swivel clamp on the end of the shaped charge units according to the invention will allow a number of shaped charge units to be successively installed in ports in a gun barrel without the requirement of exact spacing of the units with respect to the elongated detonator fuse. The swivel connection between the charge units and the clamp which receives the fuse allows the shaped charges to be tightly served within the threaded ports without twisting or binding the elongated fuse. Further, the configuration of the swivel clamp allows the elongated fuse to slide longitudinally with respect to an installed shaped charge unit to facilitate installation of other charge units without disrupting the secure connection between the fuse and the installed shaped charge unit.

Further, the unitary construction of the individual charge units allows the units to be easily stored in warehouses, and easily handled in the manner of a spark plug and the like. The integral charge units of the present invention do not require additional pieces in order to provide a secure fit Within the perforator, and are much easier to install than previously developed units.

What is claimed is:

1. In a perforating gun wherein a gun barrel is provided with explosion ports in the walls thereof and an elongated detonating fuse extends through the barrel, the combination comprising:

(a) a cap member adapted to be rotatably inserted into one of said ports,

(b) a tubular casing supported by said cap member and having a diameter less than the diameter of said port, said casing having a truncated generally coneshaped end portion disposed opposite said cap member,

(c) a hollow cone-shaped charge of explosive contained inside said casing the apex of which is directed away from said cap member, and

(d) clamp means swiveled on said end portion of said casing and having an opening therein for receiving a portion of said fuse, whereby twisting of said fuse is prevented during the insertion of said cap member into said port.

2. The combination defined in claim 1 wherein said end portion of said casing includes an annular groove about the exterior thereof, said clamp means interfitting in said groove for free rotation relative to said casing.

3. The combination defined in claim. 2 wherein said clamp means includes a pair of resilient prong members spaced apart for securely receiving a portion of said fuse.

4. A perforating gun comprising:

(a) a gun barrel having a plurality of explosion ports defined in the Wall thereof,

(b) an elongated fuse extending through said barrel,

(c) a shaped charge unit for threaded connection in each of said ports and having a length as to extend through said ports to a location adjacent a portion of said fuse,

(d) each said shaped charge unit including a quantity of explosive with a hollow cone-shape the apex of which is directed toward said fuse, and

(e) clamp means rotatably mounted on the end of each said shaped charge unit for securely receiving a portion of said fuse.

5. The apparatus defined in claim 4 wherein each said shaped charge unit comprises:

(a) a cap member adapted to threadedly engage the walls of said port, and

(b) a tubular casing supported by said cap member and having a diameter less than the port diameter, said casing having a closed truncated cone-shaped end opposite said cap member for containing said quantity of explosive.

6. The apparatus defined in claim 4 wherein each said clamp means on a shaped charge unit is adapted to be connected to a loop of said fuse drawn through one of said ports.

7. The apparatus defined in claim 4 wherein said clamp means comprises:

(a) a base swivel mounted on the end of said charge unit, and

(b) a pair of resilient prong members spaced apart on said base to securely receive a cross section portion of said fuse.

8. The apparatus defined in claim 4 wherein each said shaped charge unit has a length greater than the interior radius of said gun barrel.

9. The apparatus defined in claim 4 and further comprising:

a cone-shaped metallic liner mounted within said hollow cone shape of explosive. 10. The method of loading shaped charge units having a swivel clamp on the end thereof into threaded ports in the barrel of a well perforating gun comprising:

(a) disposing an elongated flexible fuse through the interior length of said barrel, (b) drawing a loop of said fuse outside said barrel through one of said ports, (0) connecting the swivel clarnp of a shaped charge unit to said loop of fuse outside said barrel, and

(d) inserting said loop of fuse and said shaped charge unit into said port while screwing said shaped charge unit into said threaded port.

References Cited UNITED STATES PATENTS 5 VERLIN R. PENDEGRASS, Primary Examiner. 

